The invention is a sensor protector for automatic product dispensers that include a capacitive sensor, which sensor protector provides an obstacle to prevent excess liquid from collecting on or near a sensor area in front of the capacitive sensor of the automatic product dispenser, and a method to eliminate a need for recalibration of the capacitive sensor which can otherwise occur when the sensor area in front of the capacitive sensor becomes moist or wet.
Automated dispensers of all types, such as roll paper towel dispensers, are popular in public settings since they address a need to provide a hands free way of dispensing various products, e.g., paper towels, without a user having to operate a lever, etc., to dispense the product. This helps to maintain a sanitary environment. Also, since the automatic dispensers can be set to dispense a predetermined amount of product and at predetermined intervals between dispensing the product, such automatic dispensers can help reduce product waste.
A technology used to activate the automatic dispenser is capacitive sensing, wherein a capacitive sensor (a.k.a. capacitive displacement sensor) detects a change in capacitance when something, e.g., fingers or the hands of a user, approaches the capacitive sensor, i.e., approaches a target sensing area of the capacitive sensor. The capacitive sensors function as proximity sensors. When this occurs, the capacitive sensor sends a signal to a dispenser mechanism of a dispenser, which then dispenses the product. In typical applications, the capacitive sensor is mounted inside of a plastic housing of the automatic dispenser. The thickness of the plastic in front of the sensor (the sensor area) is thin enough so that the capacitive sensor will function when a hand or fingers are placed in close proximity to the sensor area outside of the housing. Capacitive sensors are well known in the art.
In order to use the automatic dispenser, a user will place his or her hands near the sensor area outside the housing. The capacitive sensor will detect the presence of the user's hand, and will cause the automatic dispenser, e.g., an automatic roll paper towel dispenser, to dispense a length of paper towel. Sometimes a user will touch the sensor area of the housing with wet hands, leaving the sensor area moist or wet. If and when a wet hand touches the sensor area behind which the capacitive sensor is located, particularly if a lot of liquid collects on the sensor area, the capacitive sensor will often lose its set point and will temporarily be inoperative until the capacitive sensor goes through a recalibrate process. During this recalibration process, which can take thirty seconds or longer, the automatic roll paper towel dispenser will not operate. When this happens, the user may mistakenly believe that the automatic roll paper towel dispenser is out of paper or non-functional. Particularly in heavy use situations, such delays are problematic. By preventing excess liquid from accumulating on or near the sensor area, the invention prevents the need for recalibration and the associated confusion and delays caused by recalibration. As such, a device and method are desired that will prevent such problems.